diff --git a/src/dodb/storage/cached.cr b/src/dodb/storage/cached.cr
index 546f6ff..684aadb 100644
--- a/src/dodb/storage/cached.cr
+++ b/src/dodb/storage/cached.cr
@@ -35,7 +35,7 @@ end
 # │       └── Corvet -> ../../data/0000000000
 # ```
 #
-# WARNING: beware of the RAM use, see `DODB::Storage::Stacked` for a less memory-hungry option.
+# WARNING: beware of the RAM use, see `DODB::Storage::Common` for a less memory-hungry option.
 class DODB::Storage::Cached(V) < DODB::Storage(V)
 	@indexers = [] of Index(V)
 	property data = Hash(Int32, V).new
diff --git a/src/dodb/storage/common.cr b/src/dodb/storage/common.cr
index cac6fe5..1efb384 100644
--- a/src/dodb/storage/common.cr
+++ b/src/dodb/storage/common.cr
@@ -12,7 +12,7 @@
 # constantly ask for the same data over and over.
 #
 # ```
-# # Creates a DODB stacked database.
+# # Creates a DODB database for common usage (a limited number of cached entries).
 # car_database = DODB::Storage::Common.new "/path/to/db"
 #
 # # Creates a (cached) index.
@@ -37,7 +37,7 @@ class DODB::Storage::Common(V) < DODB::Storage::Cached(V)
 	# In case the number of stored entries exceeds what is allowed, the least recently used entry is removed.
 	property fifo : FIFO(Int32)
 
-	# Initializes the `StackedDataBase` with a maximum number of entries in the cache.
+	# Initializes the `DODB::Storage::Common` database with a maximum number of entries in the cache.
 	def initialize(@directory_name : String, max_entries : UInt32)
 		@fifo = FIFO(Int32).new max_entries
 		Dir.mkdir_p data_path
diff --git a/src/fifo.cr b/src/fifo.cr
index e6684fb..4f3aaf5 100644
--- a/src/fifo.cr
+++ b/src/fifo.cr
@@ -1,25 +1,28 @@
 # This class enables to keep track of used data.
 #
-# Each time a value is pushed, it is put on top of a FIFO stack.
-# Stack size is configurable, so in case the stack size exceeds what is allowed,
+# Each time a value is added, it is put in a FIFO structure.
+# Adding a value several times is considered as "using the value",
+# so it is pushed back at the entry of the FIFO (as a new value).
+# In case the number of entries exceeds what is allowed,
 # the least recently used value is removed.
-#
 # ```
 # fifo = FIFO(Int32).new 3 # Only 3 allowed entries.
 #
-# pp! fifo << 1 # -> nil (there is still room in the stack)
-# pp! fifo << 2 # -> nil (there is still room in the stack)
+# pp! fifo << 1 # -> nil (there is still room in the FIFO structure)
+# pp! fifo << 2 # -> nil (there is still room in the FIFO structure)
 # pp! fifo << 3 # -> nil (last entry without exceeding the allowed size)
 # pp! fifo << 4 # -> 1 (least recently used data)
-# pp! fifo << 4 # -> nil (already in the stack)
-# pp! fifo << 2 # -> nil (already in the stack)
+# pp! fifo << 4 # -> nil (already in the structure)
+# pp! fifo << 2 # -> nil (already in the structure)
 # pp! fifo << 5 # -> 3 (least recently used data)
 # ```
+#
+# The number of entries in the FIFO structure is configurable.
 class FIFO(V)
-	# This array is used as a *stack*.
+	# This array is used as the *fifo structure*.
 	property data : Array(V)
 
-	# Maximum allowed entries in the stack.
+	# Maximum allowed entries in the structure.
 	property max_entries : UInt32
 
 	def initialize(@max_entries : UInt32)
@@ -31,7 +34,7 @@ class FIFO(V)
 	# WARNING: implementation is extremely simple (3 lines) and not designed to be highly efficient.
 	def <<(v : V) : V?
 		@data.select! { |x| v != x }            # remove dups
-		@data.unshift v                         # push on top of the stack
+		@data.unshift v                         # push as the first value of the structure
 		@data.pop if @data.size > @max_entries  # remove least recently used entry if `@data` is too big
 	end